Experimental and numerical validation of the influence on Savonius turbine caused by rear deflector

Savonius turbine is a popular vertical shaft power generation turbine for its small starting torque and outstanding cost effectiveness. Installing the deflector on the Savonius turbine is a cost-effective way to increase its power performance. In this study, a passive positioning system is proposed, so as to settle the matter that the deflector is unable to be kept in the suitable position autonomically. The system acclimatizes itself to the inflow automatically with the help of the rear deflector that is impinged by the incoming flow. In order to demonstrate power performance of the presented system, the influence of the rear deflector on Savonius turbine is experimentally and numerically investigated through towing tank tests and 2D CFD simulations. The results indicate that: the lower deflector length and farther distance from the center of rotation, the weaker effect on the power coefficient. Considering the engineering requirements of power generation device, the optimal placement of the deflector is achieved. When the distance from the center of rotation is 0.82 times than the turbine's diameter, the suppressing effect on the power coefficient is less than 3% in this operating condition.